Newbie Support Help Internal Pressure?

[BegTech]

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Dear Sirs:

I am a newbie struggling to learn Elmer.

Attached is a relatively simple case static stress analysis case

MJ2704.zip

(163.04 KiB) Downloaded 244 times

. It is a quarter slice of a cylindrical pressure vessel, with constant pressure inside. My problem is likely with the boundary conditions. What I have tried to do is described below--but the results make little sense, so please tell me what I have missed or done incorrectly.

To make a symmetry condition at the cut in the Z plane, I have set a dirichlet 1 condition (x) to constrain displacement in the X direction to zero. Likewise for the X plane, I have constrained the Z displacement to zero. I have constrained the y displacement along the bottom edge to zero.

I have tried various tensor conditions in an attempt to get the expected output of relatively even radial displacement. None seem to work, thought I can move the displacement around and bring it to either edge of the model, so that I think the symmetry conditions are working--but I may be wrong there also.

Please Help--do I have to make another model of the fluid inside to set a uniform pressure inside the vessel, or is there a simpler way to apply pressure?

Thank you for your help.

[Franz Pichler]

Hi there,
I had look at your case and i think the use of the "Normal-Tangential Displacement" Keyword in BC number 3 is the problem. THis is thought for Dirichlet COnditions. THe Normal Force is "Normal" by itself.
Taking the keyword awy yields a more uniform solution.
And i think you hjave to be careful with the normal force sign. This force is taken in direction of the outside normal vector. In your case that means outside of BC3 and so inside the cylinder.
Change side if you want to blow up the cylinder,

best regards
Franz